The body of the female full-grown rhino was found at Kukurkata near Kathalchang forest camp in Burapahar range, Park officials said.
The animal's horns were sawn off and empty cartridge shells of AK-47 were found near the body.
Forest guards have launched a massive search operation along the Karbi Hills to apprehend the poachers who may have escaped to neighbouring Karbi Anglong district.
Another rhino had died last week due to natural causes after it got stuck in the mud at Borbeel under Kohora range of the Park.
Altogether 65 rhinos have died during the year in Kaziranga National Park with 22 due to natural causes, 23 in flood water and 20 killed by poachers.